• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1093-1094
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• 2006

City Train Technology that is large and complex system and consists of mechanical, electronic, electric, materials, computer, communication, civil/track etc. is very important area of railway industry, national fundamental industry. The standardization of city train system as a public transportation method and foundation of national economy is very important in order to do effective operation and to get fundamental technology, and the information system of the standards is required to operate the city train system effectively. By building data base of city train system design knowledge using computer-aided system engineering tool-Cradle, the system development issues and the design solutions are used by all engaged persons, and are managed by modeling and documentation. And this system will support architecture design consistently and effectively by applying this system to formalize early development process, to system requirements and configuration management, to system interface analysis and management and to system behavior analysis etc.. This study is for construction of data base of system design knowledge through making data base of many kinds of standards using CASE tool based on System Engineering Process, and introduces a model to support concurrent engineering for all engineers involved in system development allowing access to standard DB through Web from anywhere and at anytime.

• Journal of the Korean Society for Railway
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• v.13 no.3
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• pp.278-282
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• 2010

Since a power supply substation of the magnetic levitation train system includes a inverter which is necessary to change the frequency of power, it has a different characteristic comparing to any other railway system. Nowaday a study for determining rating of facilities constituting a power supply system and modeling that system is undergoing. In this paper, a analysis model for the power supply system of the magnetic levitation train using the 3-level inverter is proposed. And the analysis for output characteristic is performed using the PSCAD/EMTDC program. The control method about the output of 3-level inverter for supplying power to loads in magnetic levitation train system is also described.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1227-1232
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• 2008

High-speed train of push-pull type called as G7 train has been developed and chosen as the model of KTX-II which will be operated on Honam Line nexr year. However, the EMU-type high-speed train appeared to be the recent trend that foreign markets have shown. Also, in the near future, a great number of new train sets are needed to accommodate the increased passengers in our country. Thus, development of the high-speed EMU was decided, planned, and started. In the development, included were almost all fundamental key technologies such as noise and vibration reduction in a passenger cabin, running characteristics, aerodynamic analysis, crashworthiness evaluation, EMI/EMC analysis, design of the cooling system for the propulsion control system, enhanced performance of transformer and switching converters, synchronous traction motor with permanent magnets, new design of front nose and ergonomic interiors, application of advanced information technology(IT) and smart sensors and the cost reduction of construction of railway bridges, etc. Each key technologies are carried out as sub-project independently but under the supervision of a project. The project will develop the high advanced level of technologies and provide necessary know-why's and support the team in charge of the development of the high-speed EMU, Hyundai Rotem Co. Ltd. The high-speed EMU will be successfully developed with the support of the project.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.7
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• pp.827-833
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• 2011

In this study, a simulation model to estimate the current-collection performance of a high-speed train was developed by using a commercial finite element analysis software, SAMCEF. A three-dimensional springDdamperDmass model of a pantograph was created, and its reliability was validated by comparing the receptance of the model to that of the actual pantograph. The wave propagation speed of the catenary model was compared with the analytical wave propagation speed of the catenary system presented in the UIC 799 OR standard. The length of the droppers was controlled, and the pre-sag of the contact wire due to gravity was considered. The catenary and the pantograph were connected by using a contact element, and the contact force variation when the pantograph was moved at velocities of 300 km/h and 370 km/h was obtained. The average, standard deviation, maximum, and minimum values of the contact force were analyzed, and the effectiveness of the developed simulation model was examined.

• Journal of The Korean Society For Urban Railway
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• v.6 no.4
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• pp.319-326
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• 2018

The safety interval to prevent collision between trains in a train control system is based on the braking distance according to the emergency braking of the train. The evaluation of the braking performance is based on the longitudinal train dynamics or the commissioning test in the test track, but since the conditions such as the weakening of the adhesion coefficient between the wheel and rail can not all be considered, these conventional methods are not sufficient to design of the train control systems. Therefore, in this study, the Monte Carlo Method (MCM) which can consider various environments is used to analyze braking performance and limitations. The braking model is based on the air braking used in the emergency braking and is modeled to take into account the braking pressure, efficiency, friction coefficient, adhesion condition, and vehicle mass distribution. It is confirmed that braking performance can be improved by controlling the quality of braking device. In addition, the change of the braking performance was confirmed according to the vehicle constituting the train. The results of this study are expected to be used as basic information for designing safety clearance for the train control systems and as a basis for improving the braking performance of railway vehicles.

• International journal of advanced smart convergence
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• v.8 no.4
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• pp.75-81
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• 2019

Though recent advancement of deep learning methods have provided satisfactory results from large data domain, somehow yield poor performance on few-shot classification tasks. In order to train a model with strong performance, i.e. deep convolutional neural network, it depends heavily on huge dataset and the labeled classes of the dataset can be extremely humongous. The cost of human annotation and scarcity of the data among the classes have drastically limited the capability of current image classification model. On the contrary, humans are excellent in terms of learning or recognizing new unseen classes with merely small set of labeled examples. Few-shot learning aims to train a classification model with limited labeled samples to recognize new classes that have neverseen during training process. In this paper, we increase the backbone depth of the embedding network in orderto learn the variation between the intra-class. By increasing the network depth of the embedding module, we are able to achieve competitive performance due to the minimized intra-class variation.

• Journal of the Korean Society for Railway
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• v.4 no.4
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• pp.147-154
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• 2001

A high-speed rail system represents a typical example of large-scale multi-disciplinary systems, consisting of subsystems such as train, electrical hardware, electronics, control, information, communication, civil technology etc. The Systems Engineering, as a methodology for engineering and management of today's ever-growing complex system, must be applied to development of such systems. This paper presents systems engineering framework model to have to be applied to the systems engineering technology development task for the korean next-generation high-speed railway systems in progress and demonstrates data models and schema for computer-aided systems engineering software, RDD-100, for use in its development and management.

• Journal of the Korean Society for Railway
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• v.4 no.3
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• pp.94-101
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• 2001

One of the best methods to evaluate crashworthiness of a full rake trainset is to analyse 1-dimensional dynamic model using dampers, nonlinear springs and bars, and masses. In this study, the crashworthiness of KHST has been evaluated by analysing a nonlinear dynamic model made up of springs/bars-dampers-masses. The numerical results show that the KHST can absorb more kinetic energy at lower impact forces and lower accelerations in case of heavy collisions, if compared with KTX. Also, the KHST can be protected from any damage in its car-body and electric components except the energy absorbing tube in case of light collisions, like train-to-train accidents at speed under 8 kph. On the other hand, the KTX may be more damaged in the light collisions because there is no energy absorbing tube.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.239-246
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• 2009

The Mode I interlaminar fracture toughness of woven fabric carbon/epoxy and glass/epoxy composites for a train carbody was measured and FEM analysis was conducted. The woven fabric epoxy composite manufactured by hand lay-up, has high stiffness and strength, good resistance for impact, fatigue, corrosion and in-plane failure. The DCB(Double Cantilever Beam) specimen made of woven fabric epoxy composite had the size of 180mm $\times$ 25mm $\times$ 5mm and the insert of 65mm. The Mode I interlaminar toughness of specimen was measured according to ASTM 5528-01. The crack propagation behavior of the DCB specimen was simulated using FEA with cohesive elements that model the adhesive layer between woven fabric plies.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1069-1077
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• 2009

For external noise prediction of railway vehicles, sophisticated individual source modelling as well as appropriate noise propagation model from the sources is necessary to ensure the accuracy of the predicted results and contributions of each equipment to the overall noise levels. Accurate and reasonable identification procedures of sound sources of equipment including source strength, directivity and positions installed in the train play an important role in a prediction model, since it is not easy to establish a simple model for the sources with a single rule due to the complexity of source characteristics of equipment in size and directivity pattern. This paper guidelines practical considerations for identification of noise sources in railway vehicles including typical source characteristics of several sub-systems that emits noise to the environment, particularly for electric multiple unit(EMU), and verify effectiveness of assumptions used in the modelling of equipment by measurement with a simple part. The predicted external noise level of a complete train using Exnoise, which was developed by Hyundai-Rotem and has been verified in the a lot of field-tests, incorporating source modelling considered in this paper shows close correlation with the measured ones.